how do you verify your address with your local 911 operator without calling them?

The only address they would have would be the address that you've entered in Vonage. Or am I missing something in your question?

Not true - that's a bad assumption.

Others have called (yes, called 911 - some centers have a non-emergency number, or allow you to be immediately transferred to a non-emergency line) and found that a completely different address is listed for them.